"Doghouse Riley" wrote in
message news
I wouldn't bother with a thermostat, if it's a small pond just get a
floating pond heater and turn it on when the weather looks like it's
going to freeze, the temperature for goldfish isn't that critical, koi
would be a different matter.
Doghouse Riley
Surely Koi won't be a problem as they should have a deep pond in which to
live. A pal of mine had a six ft deep pond which held some really impresive
Koi.
At this depth a bit of surface ice would cause no problems.
Bill